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Anonymous Poster

When Will a VSD (Variable Speed Drive) Cause a 4 Pole Motor to Vibrate at 50Hz?

07/31/2010 11:13 PM

Bearing vibration experts from a company had told me my 100KWatt VSD is faulty thus causing the motor to vibrate when running above 47Hz and below 53Hz. With no v-belts connected to the 6 belt pully, i.e. just motor and pully, then it seems to run smooth. When connecting belts the friction press flywheel starts to vibrate.

Can it be that the pully is out of balance, or perhaps the pully and motor rotor?

If the motor fan, rotor and pulley is in perfect balance, can a defect in the motor windings cause vibration?
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Tornado
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#1

Re: When will a VSD(variable speed drive) cause a 4pole motor to vibrate at 50Hz?

08/01/2010 12:01 AM

Maybe there is a resonance at ~50Hz in the system that the motor drives?

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Anonymous Poster
#2
In reply to #1

Re: When will a VSD(variable speed drive) cause a 4pole motor to vibrate at 50Hz?

08/01/2010 2:26 AM

WITH ELECTRICAL RESONANCE THE MOTOR WILL SIMPLY BURN.
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Tornado
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#3
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Re: When will a VSD(variable speed drive) cause a 4pole motor to vibrate at 50Hz?

08/01/2010 2:51 AM

OH, WOW, I NEVER WOULD HAVE GUESSED. <Turning off stupid all-caps now...> I simply focused on mechanical resonances I have heard about. Electrical resonances might also be interesting, but none were explained.

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Simon Wan
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#4

Re: When Will a VSD (Variable Speed Drive) Cause a 4 Pole Motor to Vibrate at 50Hz?

08/02/2010 12:12 AM

VSD will not cause any vibration to the motor if you run at 50Hz or 60Hz or below 50Hz. Since you have uncouple the belting and running your motor with only the motor and the pulley, it seem to be O.K. without any vibration.

Therefore, the vibration may come from your motor itself. Check the driving and non driving end of the motor bearing condition including the bearing housing and also your flywheel bearing.

Sometime, when you run at slow speed, vibration may not able to be detected but at high speed the vibration is there. We have the same problem with our main fan and finally we discover that the fan shaft bearing was worn out. At low speed it was O.K. But at High speed vibration is there. After changing the bearing the vibration was gone.

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jakbeuk
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#7
In reply to #4

Re: When Will a VSD (Variable Speed Drive) Cause a 4 Pole Motor to Vibrate at 50Hz?

07/12/2012 11:44 PM

Is this motor of substantial size? I had a 150kW 3phase induction motor that vibrated, we checked the bearings and they were fine, but noise inside the motor caused us also to have a look as to what caused an increase in current and heat to the point where the motor started to trip the protection-------stripping the motor, we found damaged rotor bars.

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JRaef
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#5

Re: When Will a VSD (Variable Speed Drive) Cause a 4 Pole Motor to Vibrate at 50Hz?

08/02/2010 12:42 PM

It is possible that if you are using Sensorless Vector Control (SVC) with your VFD, it may cause vibration if it was not tuned properly. The reason it would go away when the pulley is disconnected is because the problem would only appear under some amount of load, maybe even just the pulley itself.

But before I type a lot of pointless stuff about tuning an SVC drive and it turns out you don't have one, is that what you are using? If so, the first thing to try is to change to V/Hz operating mode. If the problem persists, that's not what it was and most likely it's a problem with your pulley.

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jakbeuk
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#6
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Re: When Will a VSD (Variable Speed Drive) Cause a 4 Pole Motor to Vibrate at 50Hz?

08/03/2010 1:45 AM

Can you please tell me more about this"not tuned properly" as our VSD or VFD as you call it does offer a "self tune option but wasn't employed at first installation as we were uncertain what this would do in the end.

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